Preheat oven to 350°F. Line an 8-inch square baking pan with aluminum foil, making sure to leave some overhang for easy removal. Set aside.

In a large mixing bowl, mix together the flour, sugar, and salt. Cut the butter into pieces and add it to the mixture. Using a mixer, beat on low speed until you have coarse crumbs (you can also use a fork or your hands). Reserve 1 cup of the mixture and transfer to a separate mixing bowl. Mix in ¼ cup of the shredded coconut with the reserved mixture, cover tightly, and transfer to the refrigerator. Scoop the remaining crumb mixture into the prepared baking pan and firmly press it down into an even layer.

Bake at 350°F for about 18-20 minutes or until the top is set and the edges are lightly golden brown. Remove from the oven and set aside to cool.

To make the pineapple coconut filling:

Mix together the crushed pineapple, sugar, cornstarch, and lemon juice in a large saucepan. Cook over medium heat, stirring often, for about 5-7 minutes or until the pineapple mixture has thickened. Remove from the heat and stir in the remaining ½ cup of shredded coconut.

Pour the pineapple filling over the crust. Remove the remaining crumb topping from the refrigerator and and sprinkle it evenly over the top. Return to the oven and bake at 350°F for 30-40 minutes or until lightly golden brown on the top.

Remove from the oven and transfer to a wire rack to cool. Remove the foil from the pan, slice into bars, and enjoy.